Muffler for pneumatic tools

ABSTRACT

A muffler for removably installing onto a pneumatic tool. A muffler housing has a deflector plate dividing the tool exhaust gases into streams of gas. The streams impinge upon an airfoil rotatably mounted within the housing mixing the streams and gas pulses in a more uniform mixture which then is emitted from the housing.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

The present invention relates generally to the field of mufflers for abating noise.

DESCRIPTION OF THE PRIOR ART

United States OHSA regulations mandate a maximum noise level for pneumatic tools used in various environments, such as, in mines. Jackhammers typically employ pressurized gas periodically forced against a ground-engaging tool. As a result, pulses of exhaust gas are emitted via the exhaust port of the pneumatic tool at high noise levels of approximately 115 decibels. OHSA regulations stipulate that an operator of a pneumatic tool shall not be exposed to noise levels over an eight-hour period in excess of 86.2 decibels unless the operators are provided with ear protection.

In a mining environment, the pneumatic tool exhaust noise is accentuated due to the rocky mine walls. It is therefore desirable to provide some type of a muffler that may be installed on existing pneumatic tools.

It is known to provide mufflers with internal combustion engines for reducing exhaust noise. Most mufflers employ various baffles to route the exhaust gases through a maze in an attempt to reduce and mix the pulses of gas emitted by the cylinders of the engine. Another approach is to use a muffler employing a turbine to cause the exhaust gases to flow in a rotational direction while passing through various channels causing a muffling affect in the air flow without restricting the air or causing excessive back pressure. The turbine approach is employed in the device disclosed in U.S. Pat. No. 6,679,351 issued to Cummings et al.

Many of the prior mufflers are relatively large and if installed on a pneumatic tool would make the tool unwieldy and dangerous in use. There is therefore a need for a relatively compact muffler that may be installed on a pneumatic tool to significantly reduce exhaust noise. Since there are many pneumatic tools already in use, such a muffler should be removably installable to existing pneumatic tools eliminating the necessity for purchase of an entirely new tool with muffler. Disclosed herein is such a muffler.

SUMMARY OF THE INVENTION

One embodiment of the present invention is a muffler to reduce noise associated with pulses of exhaust gas emitted by an exhaust outlet of a pneumatic tool comprising a housing to mount to a pneumatic tool to receive exhaust gas therefrom. The housing has an inlet and a plurality of exhaust ports. The housing further has a chamber positioned between the inlet and the exhaust ports. A deflector is positioned between the inlet and the exhaust ports to receive pulses of exhaust gas emitted by the pneumatic tool to deflect the pulses into a plurality of streams of gas. An airfoil is rotatably mounted within the chamber and positioned between the deflector and the exhaust ports to receive and mix the streams of gas and mix the pulses of exhaust gas thereby reducing the noise associated with the pulses of exhaust gas.

It is an object of the present invention to provide a muffler for a pneumatic tool.

A further object of the present invention is to provide a muffler that may be removably mounted to a pneumatic tool to significantly reduce exhaust noise.

In addition, it is an object of the present invention to provide a pneumatic tool having a muffler to significantly reduce exhaust noise.

A further object of the present invention is to provide a new and improved muffler for reducing exhaust noise.

Related objects and advantages of the present invention will be apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded fragmentary view of a pneumatic tool having an exhaust muffler.

FIG. 2 is an end view of the muffler housing showing the exhaust ports.

FIG. 3 is an end view of the muffler housing taken along the line and viewed in the direction of arrows 3-3 of FIG. 1 showing the deflector plate.

FIG. 4 is a cross-sectional view of the muffler housing taken along the line and viewed in the direction of arrows 4-4 of FIG. 1.

FIG. 5 is an end view taken along the line and viewed in the direction of arrows 5-5 of FIG. 1 showing the seal and nipple.

FIG. 6 is an end view of the device for mounting the muffler housing to a pneumatic tool taken along the line and viewed in the direction of arrows 6-6 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring now more particularly to FIG. 1, there is shown an exploded fragmentary view of a pneumatic tool 20 with exhaust muffler to abate the noise associated with the exhaust gases emitted by the tool. The muffler includes a muffler housing 21, seal 50, nipple 40, and mounting device 70 all connected together to the exhaust port of a standard pneumatic tool 60.

A variety of pneumatic tools are commercially available. A portion of pneumatic tool 60 (FIG. 1) has a circular shaped exhaust outlet 61 leading from the exhaust passage 74, in turn, in fluid communication with the cylinder outlets or exhaust valves of the engine. A cylindrical flange or wall 62 extends inwardly from the tool portion 60 surrounding outlet 61 and defines an inwardly facing continuous ring shaped surface 63 to receive mounting device 70 to secure the muffler to the pneumatic tool portion 60.

Mounting device 70 includes a flange shaped end 71 integrally attached to a threaded main body 73 having a reduced diameter opposite end 75. Mounting device 70 is hollow forming a passage to allow the exhaust gases within passage 74 to flow through nipple 40, seal 50, and into muffler housing 21.

In order to install mounting device 70 to the exhaust outlet 61 of a standard pneumatic tool 60, a slot 76 is provided that extends the entire length of mounting device 70 from end 75 to and through flange end 71. Slot 76 thereby forms mutually opposing surfaces 77 and 78 (FIG. 6). The mounting device may be produced from an elastic material allowing ends 77 and 78 to be squeezed together thereby reducing the diameter of flange end 71 allowing flange end 71 to be slipped through outlet 61 and into passage 74. Upon release of the mounting nut, edges 77 and 78 will separate thereby causing the flange end to assume its normal enlarged position preventing accidental disengagement of the mounting device from passage 74. Flange 71 has an undersurface 72 that abuts the inwardly facing surface 63 formed by flange 62 providing a stop means for limiting movement of mounting device 70 outwardly from the tool.

Muffler housing 21 is hollow having an inlet 23 and a plurality of exhaust ports 24 with a chamber formed therebetween (FIG. 4). In one embodiment, housing 21 has a length of 2¾ inches and an outside diameter of 2 inches.

A deflector wall 25 is fixedly mounted within housing 21 and is perpendicularly arranged relative to the longitudinal axis of the housing and also perpendicular to the flow of exhaust gas into the housing. Deflector plate 25 has a plurality of holes 26 extending therethrough to allow the exhaust gases to pass from one side of the deflector plate to the opposite side of the plate.

A rod 30 is fixedly mounted to and extends between deflector plate 25 and the exhaust port end 35 of the housing. The rod may be affixed to plate 25 and housing 21 by any conventional means. For example, a threaded bolt may be used to form rod 30 with the bolt passing through deflector plate 25 and the head of the bolt resting against plate 25 between the plate and the pneumatic tool. The opposite end of the bolt may be threaded and extend through end 35 of the housing being secured there to by a conventional internally threaded fastener 31.

A conventional bearing 33 is mounted to rod 30 and mountingly receives an airfoil 32 rotatably mounted thereto. The airfoil may take any conventional shape such as a propeller blade. Airfoil 33 freely spins on rod 30 and distributes the exhaust gas passing through holes 26 to the exhaust ports 24 while mixing the gas thoroughly.

Nipple 40 includes a cylindrical shaped main body 42 integrally attached to a cylindrical shaped enlarged end 41. The outside diameter of main body 42 is smaller than the inside diameter of muffler housing 21 to enable the main body of the nipple to slip inside the housing.

A conventional ring shaped seal 50 is positioned adjacent deflector plate 25 and is forced there against by the distal end 46 of main body 42. The nipple is secured to the housing by means of a conventional fastening device, such as a set screw 27, that extends through the wall of housing 21 adjacent cylindrical main body 42 limiting relative motion between the nipple and the muffler housing.

A passage extends through nipple 40 and seal 50 to allow the exhaust gases escaping passage 74 via mounting device 70 to move into the chamber formed by housing 21. The internal passage of nipple 40 is internally threaded and is meshingly engaged with the external threads provided on the cylindrical main body 73 of mounting device 70. Thus, in the fully assembled state, nipple 40 is threadedly mounted to mounting device 70 forcing surfaces 63 and 72 to be in contact and with housing 21 then slipped onto main body 42 to force seal 50 against deflector plate 25 with set screw 27 securing the nipple to the muffler main housing.

In operation, tool 60 emits pulses of exhaust gases into the muffler with the pulses impinging on deflector plate 25. Deflector plate 25 divides the exhaust pulses of gas into a plurality of streams of gases moving into the chamber having the airfoil 32 located therein. Airfoil 32 receives the streams of exhaust gases causing the airfoil to spin thereby mixing the streams of gas together while also mixing the individual pulses of exhaust gases providing a more uniform exhaust gas mixture. The mixture of gas then flows out of the muffler via exhaust ports 24. The noise associated with the gases flowing outward from exhaust ports 24 is considerably reduced since the discreet exhaust pulses emitted by the pneumatic tool have been mixed together. In one embodiment, the decibel level associated with the pneumatic tool exhaust is reduced from 117 decibels to a noise level less than 90 decibels.

Many variations are contemplated and included in the present invention. For example, deflector plate 25 (FIG. 3) is shown as having eight holes 26 extending therethrough while the exhaust ports 24 are shown in FIG. 2 as numbering a total of four. The present invention includes a deflector plate having more or less than eight such holes 26 while the exhaust ports may vary in number from the number less than four to greater than four.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. 

1. A muffler to reduce noise associated with pulses of exhaust gas emitted by an exhaust outlet of a pneumatic tool comprising: a housing to mount to a pneumatic tool to receive exhaust gas therefrom, said housing having an inlet and a plurality of exhaust ports, said housing further having a chamber positioned between said inlet and said exhaust ports; a deflector positioned between said inlet and said exhaust ports to receive pulses of exhaust gas emitted by a pneumatic tool and to deflect said pulses into a plurality of streams of gas; and, an airfoil rotatably mounted within said chamber and positioned between said deflector and said exhaust ports to receive and mix said streams of gas and mix the pulses of exhaust gas reducing the noise associated with the pulses of exhaust gas emitted by the pneumatic tool.
 2. The muffler of claim 1 and further comprising: a mounting device having an expanded configuration and a reduced configuration and being squeezable from said expanded configuration to said reduced configuration to fit into an exhaust outlet of a pneumatic tool and then expanded to said expanded configuration to be held therein.
 3. The muffler of claim 2 wherein: said mounting device has a threaded end to be received by said housing.
 4. The muffler of claim 3 wherein: said mounting device has a flanged end extending radially outward of said threaded end and is hollow from said flanged end to said threaded end to allow gas to pass therethrough, said mounting device has a slot extending from said threaded end to said flanged end to allow said mounting device to be squeezed to said reduced configuration to fit into an exhaust outlet of a pneumatic tool.
 5. The muffler of claim 3 and further comprising: a nipple receiving said threaded end of said mounting device, said nipple extending into said housing and having a distal end; and, a seal positioned between and against said distal end and said deflector.
 6. The muffler of claim 2 and further comprising: a rod extending between and mounted to said deflector and said housing, said deflector is fixedly mounted within said housing, said airfoil is rotatably mounted to said rod and freely spinable thereon.
 7. The muffler of claim 2 wherein: said deflector includes at least six holes extending therethrough and said housing has as at least four exhaust ports.
 8. A pneumatic tool with a muffler to abate noise associated with exhaust gases emitted by the tool comprising: a pneumatic tool having an exhaust outlet to emit pulses of exhaust gas; a muffler removably mounted to said exhaust outlet of said pneumatic tool; and, a mounting device having an expanded configuration and a reduced configuration and being squeezable from said expanded configuration to said reduced configuration to fit into said exhaust outlet of said pneumatic tool and then expanded to said expanded configuration to be removably held therein.
 9. The muffler of claim 8 wherein: said mounting device has a threaded end to be received by said muffler.
 10. The tool of claim 9 wherein: said mounting device has a flanged end extending radially outward of said threaded end and is hollow from said flanged end to said threaded end to allow gas to pass therethrough, said mounting device has a slot extending from said threaded end to said flanged end to allow said mounting device to be squeezed to said reduced configuration to fit into said exhaust outlet of said pneumatic tool.
 11. The tool of claim 10 wherein said muffler includes: a housing to mount to said pneumatic tool to receive exhaust gas therefrom, said housing having an inlet and a plurality of exhaust ports, said housing further having a chamber positioned between said inlet and said exhaust ports; a deflector positioned between said inlet and said exhaust ports to receive pulses of exhaust gas emitted by said pneumatic tool and to deflect said pulses into a plurality of streams of gas; and, an airfoil rotatably mounted within said chamber and positioned between said deflector and said exhaust ports to receive and mix said streams of gas and mix the pulses of exhaust gas reducing the noise associated with the pulses of exhaust gas emitted by said pneumatic tool.
 12. The tool of claim 11 wherein said muffler includes: a nipple receiving said threaded end of said mounting device, said nipple extending into said housing and having a distal end; and, a seal positioned between and against said distal end and said deflector.
 13. The muffler of claim 12 wherein said muffler includes: a rod extending between and mounted to said deflector and said housing, said deflector is fixedly mounted within said housing, said airfoil is rotatably mounted to said rod and freely spinable thereon.
 14. A muffler to reduce noise associated with pulses of exhaust gas emitted by an exhaust outlet of a pneumatic tool comprising: housing means to mount to a pneumatic tool to receive exhaust gas therefrom, said housing means having an inlet and a plurality of exhaust ports, said housing means further having a chamber positioned between said inlet and said exhaust ports; deflector means positioned between said inlet and said exhaust ports to receive pulses of exhaust gas emitted by a pneumatic tool and to deflect said pulses into a plurality of streams of gas; and, gas mixing means rotatably mounted within said chamber and positioned between said deflector means and said exhaust ports to receive and mix said streams of gas and mix the pulses of exhaust gas reducing the noise associated with the pulses of exhaust gas emitted by the pneumatic tool.
 15. The muffler of claim 14 and further comprising: mounting means having an expanded configuration and a reduced configuration and being squeezable from said expanded configuration to said reduced configuration to fit into an exhaust outlet of a pneumatic tool and then expanded to said expanded configuration to be held therein.
 16. The muffler of claim 15 and further comprising: a nipple receiving said threaded end of said mounting device, said nipple extending into said housing and having a distal end; sealing means positioned between and against said distal end and said deflector; a rod extending between and mounted to said deflector means and said housing, said deflector means is fixedly mounted within said housing, said mixing means is rotatably mounted to said rod and freely spinable thereon. 